The congressman leading the investigation into the Internal Revenue Service is accusing the FBI of blocking the inquiry.

The Washington Times reports Rep. Darrell Issa, R-Calif., along with Rep. Jim Jordan, R-Ohio, is threatening subpoenas to get information from the FBI Director James B. Comey Jr.

Rep. Issa is looking into the possible IRS targeting of Tea Party and other conservative groups by holding up their tax exempt status before recent elections.

It's been six months since the investigation began and the FBI still has yet to release any information.

"The department's tactics have impeded a congressional investigation and interfered with the committee's access to documents and information. Obstructing a congressional investigation is a crime," Issa and Jordan and in their letter to Comey.

They warned that if they don't get the information they will use "compulsory" means. They set a Dec. 16 deadline.